Murphy's Law and Leaky Eheim / Help

I hope someone here has a tip that they can offer. I cleaned my
lovely algae tank and started over with flourite and plants. I moved
my eheim 2026 to that tank, got it all set up and it leaks. Some
months ago I had this problem and it turned out to be something
minor. I can't recall now what the problem was and I'm getting
nowhere in trying to stop the leak. I've taken everything apart,
including the head, cleaned and lubed all the O-rings with vaseline.
Nothing works. It's leaking from inside the head (where the
electrical cord comes out) and eventually spilling over. I'm out of
ideas. If you have any ideas, please let me know. This filter was
working fine a few weeks ago when I took it off my 55, so I'm stumped.
That's what I get for specializing in algae, I guess.
JoAnn - frustrated in Pueblo, Co.